const $ = (selector, doc = document) => doc.querySelector(selector);

const isDOMExist = (selectors) => {
  return Object.keys(selectors).map(key => {
    const selector = selectors[key];
    const el = $(selector);
    return {
      selector,
      exist: !!el,
    };
  });
};

// test
console.table(isDOMExist({ // 初次回答
  iframe: '#edui1_iframeholder iframe',
  submitBtn: '.new-editor-deliver-btn',
}));